title: The effects of pharmacological treatment on functional brain connectome in obsessive-compulsive disorder.
abstract: BACKGROUND
  Previous neuroimaging studies of obsessive-compulsive disorder (OCD) have reported both baseline functional alterations and pharmacological changes in localized brain regions and connections; however, the effects of selective serotonin reuptake inhibitor (SSRI) treatment on the whole-brain functional network have not yet been elucidated.
  
  
  METHODS
  Twenty-five drug-free OCD patients underwent resting-state functional magnetic resonance imaging. After 16-weeks, seventeen patients who received SSRI treatment were rescanned. Twenty-three matched healthy control subjects were examined at baseline for comparison, and 21 of them were rescanned after 16 weeks. Topological properties of brain networks (including small-world, efficiency, modularity, and connectivity degree) were analyzed cross-sectionally and longitudinally with graph-theory approach.
  
  
  RESULTS
  At baseline, OCD patients relative to healthy control subjects showed decreased small-world efficiency (including local clustering coefficient, local efficiency, and small-worldness) and functional association between default-mode and frontoparietal modules as well as widespread altered connectivity degrees in many brain areas. We observed clinical improvement in OCD patients after 16 weeks of SSRI treatment, which was accompanied by significantly elevated small-world efficiency, modular organization, and connectivity degree. Improvement of obsessive-compulsive symptoms was significantly correlated with changes in connectivity degree in right ventral frontal cortex in OCD patients after treatment.
  
  
  CONCLUSIONS
  This is first study to use graph-theory approach for investigating valuable biomarkers for the effects of SSRI on neuronal circuitries of OCD patients. Our findings suggest that OCD phenomenology might be the outcome of disrupted optimal balance in the brain networks and that reinstating this balance after SSRI treatment accompanies significant symptom improvement.
authors.affiliation: Department of Brain and Cognitive Sciences-World Class University Program, College of Natural Sciences, Seoul, Republic of Korea.
authors.forename: Da-Jung
authors.initials: DJ
authors.lastname: Shin
authors.affiliation: Institute of Human Behavioral Medicine, Seoul National University-MRC, Seoul, Republic of Korea.
authors.forename: Wi Hoon
authors.initials: WH
authors.lastname: Jung
authors.affiliation: State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: He
authors.affiliation: State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China; Center for Cognition and Brain Disorders, Hangzhou Normal University, Hangzhou, China; Zhejiang Key Laboratory for Research in Assessment of Cognitive Impairments, Hangzhou, China.
authors.forename: Jinhui
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Psychiatry, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors.forename: Geumsook
authors.initials: G
authors.lastname: Shim
authors.affiliation: Institute of Human Behavioral Medicine, Seoul National University-MRC, Seoul, Republic of Korea; Department of Psychiatry, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors.forename: Min Soo
authors.initials: MS
authors.lastname: Byun
authors.affiliation: Department of Psychiatry, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors.forename: Joon Hwan
authors.initials: JH
authors.lastname: Jang
authors.affiliation: Institute of Human Behavioral Medicine, Seoul National University-MRC, Seoul, Republic of Korea; Department of Psychiatry, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors.forename: Sung Nyun
authors.initials: SN
authors.lastname: Kim
authors.affiliation: Institute of Human Behavioral Medicine, Seoul National University-MRC, Seoul, Republic of Korea.
authors.forename: Tae Young
authors.initials: TY
authors.lastname: Lee
authors.affiliation: Department of Psychiatry, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors.forename: Hye Youn
authors.initials: HY
authors.lastname: Park
authors.affiliation: Department of Brain and Cognitive Sciences-World Class University Program, College of Natural Sciences, Seoul, Republic of Korea; Institute of Human Behavioral Medicine, Seoul National University-MRC, Seoul, Republic of Korea. Electronic address: kwonjs@snu.ac.kr.
authors.forename: Jun Soo
authors.initials: JS
authors.lastname: Kwon
mesh_terms: D000328:Adult; D001921:Brain / Q000187:drug effects* / Q000503:physiopathology*; D063132:Connectome / Q000379:methods; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D009434:Neural Pathways / Q000187:drug effects / Q000503:physiopathology; D009771:Obsessive-Compulsive Disorder / Q000188:drug therapy* / Q000503:physiopathology*; D011569:Psychiatric Status Rating Scales; D017367:Selective Serotonin Reuptake Inhibitors / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D017367:Selective Serotonin Reuptake Inhibitors
keywords: Connectivity; OCD; SSRI; graph-theory; resting state fMRI; treatment